There are paucity of data regarding delirium in the ED and its relationship to long term outcomes. To address this deficiency, we enrolled a large cohort of older ED patients and observed that patients with delirium were more likely to die at 6-months compared to those without delirium. This relationship persisted after adjusting for age, comorbidity burden, severity of illness, dementia, functional dependence, and nursing home residence. To our knowledge, our study is also the first to evaluate how delirium affects ED patients from the nursing home setting and found that delirium had a similar impact on 6-month mortality in this unique patient population. These findings add to the existing literature and provide further evidence of the independent relationship between delirium and death across different clinical settings in non-nursing home and nursing home patients.7, 8, 29
To our knowledge, only two studies have investigated delirium and its effect on long-term mortality in the ED setting. Lewis et al. found that patients with delirium were significantly more likely to die at 3-months (14% versus 8%), but they did not adjust for potential confounders.30
Kakuma et al. observed that delirium was independently associated with higher 6-month mortality (HR = 7.2, 95% CI: 1.6 – 32.3), but their study excluded ED patients admitted to the hospital, which constitute a significant proportion of the older ED patient population.31
Our study addresses these deficiencies by adjusting for potential confounders using Cox proportional hazards regression and by enrolling patients regardless of admission status. In addition to mortality, delirium has also been linked to accelerated functional and cognitive decline, prolonged hospitalization, nursing home placement, and increased health care costs in hospitalized patients.32
Though these studies have limited generalizability to the ED setting, it is likely that these same consequences will occur in older ED patients with delirium. Additional outcome-based studies conducted in ED patients must be performed to confirm these hypotheses.
Nursing home patients are frequent users of the ED and are disproportionately more susceptible to developing delirium.9
However, little is known about delirium’s affect on their outcomes.9
We observed that nursing home patients with delirium in the ED were more likely to die within 6 months compared to those without delirium. Nursing home patients have a significant financial impact on an already burdened US health care system,33
because they have higher rates of hospitalization compared to community dwelling elders.34
It is likely that delirium in nursing home patients drive a large proportion of such hospitalizations which further increases health care costs.35
In nursing home patients, health care expenditures also markedly increase around the time of death,36
which is an event that occurs with a high degree of frequency in patients with delirium. Additional research is required to better elucidate how delirium in nursing home patients affect outcomes and health care costs.
Despite being a marker of death, delirium is missed by emergency physicians in up to 75% of the cases.1, 2
This has been characterized as a serious quality of care issue,37
and may lead to higher mortality in older ED patients.31
Though the mechanisms for this are unclear, ED patients with unrecognized delirium may receive incomplete diagnostic workups and an underlying life-threatening illness may remain undiagnosed. These patients may also receive inappropriate interventions known to exacerbate delirium such as medications with anticholinergic properties or benzodiazepines.38, 39
Additionally, delirious patients who are discharged from the ED may be less likely to comprehend their discharge instructions,40
leading to poor adherence, return ED visits, and potentially increased mortality and morbidity.41, 42
The ED is ideally positioned to perform delirium surveillance because it is at the nexus of geriatric health care and serves as the gateway for the majority of hospital admissions. Consequently, the Society for Academic Emergency Medicine Geriatrics Task Force recently recommended that delirium surveillance in the ED be a key quality indicator for emergency geriatric care.43
Because the majority of delirium is the hypoactive “quiet” subtype,2
the clinical presentation can be subtle and is often missed without performing a delirium assessment.44
Currently, the Confusion Assessment Method (CAM) is the only delirium assessment validated for the ED setting. When performed by lay interviewers, this instrument is 86% sensitive and 100% specific compared to a geriatrician’s assessment.45
However, the CAM can take up to 10 minutes to perform which can be challenging in a demanding ED environment.46
Performing the CAM in high risk patients only (dementia, functional impairment, hearing impairment, or nursing home residence) may improve screening efficiency.2, 9
The CAM-ICU may be a more suitable alternative because it takes less than 2 minutes to perform, is highly reliable in physicians and nurses, is easy to use, and requires minimal training. Using only a 20-minute educational session, Pun et al. reported that bedside nurses were able to perform the CAM-ICU with a high degree of concordance with research staff raters (kappa = 0.92).47
However, the CAM-ICU still requires validation in the ED setting and delirium screening strategies that maximize accuracy yet minimize burden to the ED staff must be developed. These studies are currently ongoing.
Once delirium is diagnosed in the ED, the diagnostic evaluation should then focus on uncovering the underlying etiology.48
Infections, such as a urinary tract infection or pneumonia, dehydration, electrolyte abnormalities, central nervous system insults, and medication reactions are common causes.32
If admitted, physicians at the next level of care should be notified of the patient’s delirium status. Other than these interventions, however, the optimal management of delirium is still unclear, especially within the ED setting. Several multi-component delirium interventions have been developed for hospitalized patients and can be tailored for the ED,49, 50
but their efficacy is questionable.51
Because many of these interventions were started 24 to 48 hours after admission, early detection and early intervention of delirium in the ED may improve their effectiveness similar to what has been observed in sepsis and ST-elevation myocardial infarction care.52, 53
A multi-faceted line of research must be undertaken to develop delirium interventions specifically tailored for the ED setting and determine their cost-effectiveness using randomized control trial methodology.